Isolation and characterization of cellulase producing bacteria from Arachis hypogaea shell
Abstract
Arachis hypogaea L. also known as groundnut or peanut is a nutrient-dense legume widely cultivated for its oil, protein and bioactive compounds with significant nutritional and therapeutic potential. Groundnut shells are lignocellulosic agricultural wastes containing cellulose and may serve as suitable habitats for microorganisms capable of producing cellulase enzymes. This study investigated the isolation and partial characterization of cellulase-producing bacteria from Arachis hypogaea shells. Standard microbiological techniques were employed for bacterial isolation and purification, while morphological and biochemical characteristics were used for preliminary identification of selected isolates. Screening for cellulase production was carried out using carboxymethyl cellulose (CMC) agar and Congo red staining, where the formation of clear zones around colonies indicated cellulose degradation. A total of five distinct bacterial isolates, designated A, B, C, D, and E, were obtained from the Arachis hypogaea shell samples. Biochemical characterization identified isolates A and C as Bacillus spp. and isolate D as Pseudomonas spp. All five isolates demonstrated cellulolytic activity, although the level of activity varied among them. Isolate C exhibited the highest cellulase activity of 3.6 and produced the largest zone of clearance measuring 18 mm, while isolates A and D recorded activity values of 3.0. Isolates B and E showed lower cellulase activity values of 1.7 and 1.5, respectively. Partial characterization of the cellulase enzyme revealed an optimum pH of 3.7 and an optimum temperature of 31°C. The enzyme also showed activity toward carboxymethyl cellulose, confirming its cellulolytic property. The study concluded that Arachis hypogaea shells harbour cellulase-producing bacteria with potential relevance for cellulose degradation and agricultural waste utilization. The study recommends further purification, molecular identification, and advanced characterization of the most active bacterial isolate and its cellulase enzyme.